Electric heater for oil wells



Oct. 26, 1943. H. FREEMAN 2,332,708

ELECTRIC HEATER FOR OIL WELLS Filed Oct. 22, 1941 IN VENT OR.

HARRY E:. FREEMAN- h s HTTORNE).

Patented Oct. 26, 1943 UNITED STATES PATENT" OFFICE ELECTRIC HEATER FOR01L WELLS Harry E. Freeman, Pittsburgh, Pa.

Application October 22, 1941, Serial No. 416,059

3 Claims.

This invention relates to electric heaters, and

more particularly to those which are adapted to be lowered into anoil-well and when so disposed to heat the same by electric currentgenerated at and communicated from the surface. In the past numerousattempts have been made to provide an apparatus of the type describedwhich would satisfactorily function to soften and liquefy the congealed,solid, and semi-solid products of petroleum occurring in oil-wells aftera period of prolonged pumping and which obstruct the natural flow ofoil. So far as I am aware, none of these apparatus of the prior art havebeen very successful due to different shortcomings from the standpointof design.

It is among the objects of the present invention to provide an electricheater for oil-wells and the like which will efficiently function in thedesired manner.

Another object is the provision of an apparatus of the class describedwhich is simple and inexpensive to manufacture, operate and. main tain.

Still another object is to provide an apparatus for the purpose statedwhich will produce the desired results in a very short period of time.

The invention, then, comprises the features hereinafter more fullydescribed and as particularly pointed out in the claims, the followingdescription and the annexed drawing setting forth in detail a certainillustrative embodiment of the invention, this being indicative of butone of a number of ways in which the principles of the invention may beemployed.

In said drawing:

Figure l is a vertical elevation, mostly in section, of the apparatus ofthe present invention, illustrating the position it will assume when inoperation.

Figure 2 is a view similar to that of Figure 1, but at right anglesthereto, some of the parts thereof being shown in positions they willoccupy during one stage of their operation, as will be described morefully hereinafter.

Figure 31s a flow diagram illustrating the manner in which primary andsecondary circulation and agitation is provided, whereby the rate ofheating of the oil well is materially increased.

Referring more particularly to the drawing, the numeral 2 designates anelongated tube defining a vertical passageway having a liquid intakeport 3 at the bottom thereof and a liquid exhaust port 4 at the top.This tube 2 is adapted to receive oil in liquid form through the intakeport 3, vaporize the same, and to discharge the vaporized oil throughthe exhaust port 4 at the upper end of the tube after it has attained apredetermined temperature.

Adjacent its inlet port 3 the tube 2 is provided with a check valve 1from which there depends an anchor pipe 9 having perforations l0 thereinto permit the ingress of oil in liquid form.

To the upper end of the tube 2 there is secured an upper header l2having a pressure dome l4 therein. The exhaust port 4 of the tube 2communicates with the pressure dome I4 by means of a check valve I6.From the pressure dome l4 the vaporized oil is diffused through a seriesof apertures l8 arranged in the side wall of the upper header l2.

In order to enable the softening and liquefication of the congealed,solid, or semi-solid products of petroleum, and the vaporization ofliquid oil which is received within the tube 2, there is arranged aroundand exteriorly of the latter a plurality of superposed electricalheating elements 20 which are electrically conected to each other inorder that all may be energized from a single source.

Preferably these electrical heating elements 20 are tubular-shaped, andare assembled by telescoping th same over the tube 2. Preferably, too,the superposed electrical heating elements 20 are electrically connectedfor quick detachability and reassembly, in order to enable rapidreplacement. For this purpose there may be employed a bayonet type ofconnector which is generally indicated in figure at 22.

The superposed electrical heating elements 20 are enclosed by a tubularcasing 24 which extends between the lower and upper headers 6 and I2,respectively.

The uppermost of the electrical heating elements 20 is supplied withelectric current from an input wire 26 which leads to the surface of theWell and is connected to a suitable source of energy (not shown). Thisinput wire 26 is connected to a conductor 21 which extends through theupper header I2 and makes contact with the upper end of the wire of theuppermost electrical heating element 20 in any suitable manner. Thelower end of the wire of the lowermost electrical heating element 20 isgrounded to the tube 24 by means of a conductor clip 30, thus completingthe circuit.

The lowermost of the electrical heating elements 2!] rides upon aretainer spring 32 which encricles the tube 2 and rests upon a lock ring33 which is secured to the latter. This contruction and arrangementpermits the electrical ments are energized through the input wire 26,there will be softened and liquefied the con gealed, solid andsemi-solid products of petroleum occurring in oil-wells after a periodof prolonged pumping, which obstruct the natural flow of oil. The checkvalve assembly carried on the lower end of the tube 2, and exterlorly'of the lower header 6, admits liquefied oil into the tube 2 after it hasreached a predetermined temperature. In this manner liquefied oil risesin, the tube 2 until it reaches the check valve it, which providescommunication between the exhaust port 4 of the tube 2 and the pressuredome l4 provided within the upper header I2. The check valve 16 remainsclosed until the liquefied oil within the tube 2 reaches the boilingpoint, at which time it will open and permit the vaporized oil to bereleased into the pressure dome I4, from which it is diffused into theatmosphere in the well through the apertures 18.

In the foregoing manner there will be provided a circulation ofvaporized oil and the induction of flow of oil in the directionof thearrows B of Figure 3.

In accordance with the teachings of the invention, there is enhanced theheating and circulation of the liquefied oil by means of a primaryheater and agitator which is disposed exteriorly of the verticalpassageway provided by the tube 2. According to a permissive embodiment,this means takes the form of a series of verticallyextending tubes 40which are disposed peripherally of the tubular casing 24 and axiallyparallel therewith. Enclosing these tubes 46 is a housing member 42which is connected at its lower and upper ends to the lower and upperheaders 6 and I2, respectively. This housing member 42 is provided inits side Wall with a series of lower apertures 43 and a series of upperapertures 44 which communicate respectively with the lower and upperends of the tubes 40. It is to be noted that the tubes 40 are notprovided with check valves or other instrumentalities designed to impedethe flow of liquid oil therethrough. Accordingly the liquid oil ispermitted to flow into the apertures 43 in the lower end of the housing42 at all times, and to rise therein due to the heat imparted thereto bythe electrical heating elements 20. Thus the heated oil continuouslycirculates upwardly through the tubes 40 and out of the apertures 44adjacent the upper end of the housing 42. This provides for a continuouscirculation or agitation, as illustrated by the arrows A of Figure 3.

Due to the two separate circulating systems collectively functioning inthe manner set forth,

the rapid transfer of heat and liquefication of the oil is materiallyenhanced.

In addition to the foregoing elements, it will be understood thatnumerous refinements may be incorporated, as, for example, athermocouple (not shown) whereby the temperature attained may bedetermined from the surface of the well.

While I have shown and described certain specific embodiments of thepresent invention, it will be readily understood by those skilled in theart that I do not wish to be limited exactly thereto, since variousmodifications may be made without departing from the scope of theinvention as defined by the following claims. I claim:

1. An elongated tubular oil well heater, including a central axial flowtube having a spaced inlet and outlet, a second axial flow tube spacedlaterally from the first tube, electrical heating means adjacent to andheating both tubes, a tubular' ous ns enclosing sa tubes and tin means,the second tube having an axially spaced inlet and outlet laterallythrough said housing, an upper hollow header communicating with thecentral tube and having fluid discharge ports therein, and a pair ofaxially spaced fluid actuated valves in the central tube controlling theflow of fluid to and from the latter.

2. An elongated tubular oil well heater, including a central axial flowtube having a spaced inlet and outlet, electrical heating meanssurrounding said tube, a series of second axial flow tubes surroundingsaid heating means, atubular housing enclosing all of said tubes and theheating means, the second tubes each having an axially spaced inletandoutlet laterally through said housing, an upper hollowhe'adercommunicating with the central tube and having fluid dischargeports therein, a fluid actuated valve controlling the admission of fluidto said header, and a fluid actuated valve controlling the admission offluid to said central tube,

3. An elongated tubular oil well heater, including upper and lowerheaders and an outer tubular housing extending therebetween, the upperheader being hollow and having fluid outlets in the upper portionthereof, a flow tube communicating with the interior of the upper headerand extending centrally of the housing, said tube having a fluid intakeport, electrical heating means surrounding the tube within the housing,a tubular casing enclosing the heating means and spaced inwardly. fromthe outer housing, a second flow tube disposed between said casing andthe outer housing having a fluid inlet and outlet through the latterspaced axially of the heater, fluid actuated valves in the first flowtube spaced axially of the heater, and said second flow tube extendingin the region of the electrical heatingmeans, whereby the heat from thelatter induces a flow of oil upwardly through the first tube fordischarge through the outlets in the upper header, and sets up acontinuous heating and circulating flow in a body of oil in which theheater is immersed by flow throush said 5 6- ond flow tube.

. HARRY E. FREEMAN.

